Antiwar Republican Ron Paul shocked the political establishment this week when his presidential campaign announced that it raised $5.1 million, more money than John McCain in the latest quarter of 2007. How has a relatively unknown congressman from Texas attracted more support than a party stalwart and war hero like McCain? Answer: He is the only antiwar Republican running for president.

Polls right now show that anywhere between 54 and 66 percent of the public think that the invasion of Iraq was a mistake. Those numbers wouldn’t be possible if only antiwar liberals were answering that question in the affirmative. A number of Republicans have changed their minds about the wisdom of the invasion, and some opposed it from the beginning.

Enter the libertarian, isolationist, pro-life Paul, reaching out to Republicans who think the U.S. should bring the troops home now but who also abhor the idea of socialized medicine, higher taxes and a liberal judiciary. His recent fundraising success shows that his campaign knows how to stay on message and use the Internet to organize supporters. But here are a few things to put the Ron Paul boom into perspective:

Paul still barely registers on national polls, indicating that his support comes from a passionate but miniscule minority of Republicans. An overwhelming majority of Republicans in national polls say they would vote for Rudy Giuliani, Fred Thompson, John McCain, or Mitt Romney, all of whom supported the invasion of Iraq, supported the troop surge earlier this year and support the current policy of deferring to General David Petraeus on the pace of troop drawdowns.

Paul’s $5 million represents just 13 percent of the total amount of money the top five Republicans (Giuliani, Thompson, McCain, Romney, and Paul) raised in the last quarter. The other four raised $33 million, or 87 percent of the money.

Paul’s supporters point to the fact that he raised twice as much money this quarter as he did last quarter, but Fred Thompson managed to raise $8 million virtually from scratch. Although Thompson started “testing the waters” in June, he only started formally campaigning in September. His campaign claims that since his official announcement, he’s raised $200,000 a day. Thompson raised more in a month than Paul did in a quarter.

Another candidate who demonstrated fundraising growth in the third quarter was former Arkansas governor Mike Huckabee, who started to generate buzz after strong showings in the debates and the Iowa straw poll. His fundraising totals increased 31 percent, from $766,000 to around $1 million. Unfortunately for Huckabee, that’s unlikely to be enough money to compete during the intense lead-up to the January primaries and caucuses.

Paul’s fundraising numbers generated a lot of media attention because the antiwar Paul raised more than the pro-war McCain, the angle being that McCain’s support for the war has hurt him while Paul’s opposition has increased his viability. This narrative only gets the story half right. It’s true that Paul’s unique position as the only antiwar Republican candidate explains most of his success: Antiwar Republicans have nowhere else to go, and his campaign has used the Internet with increasing effectiveness to organize and funnel these Republicans to his website, where they can give money.

But McCain’s support for the U.S. mission in Iraq can’t explain the total collapse of his fundraising apparatus in the latest quarter. All of the leading Republican candidates supported the war and support the current policy of giving General Petraeus time to pursue his new counterinsurgency strategy in Iraq. Giuliani and Romney raised less money this quarter than last quarter, but McCain’s financial support plummeted 57 percent, from $11.5 million last quarter to only $5 million this time around. McCain is also reportedly $2 million in debt. His campaign is on life support.

Meanwhile, Paul’s campaign sees these triple-digit growth rates continuing in the fourth quarter. According to his website, he’s aiming to raise $4 million this month and $12 million by the end of December. One of the most interesting possibilities floating around out there is that, after the primaries are over, Paul could offer an antiwar, pro-life, third-party alternative to either Rudy Giuliani or Hillary Clinton (in 1988 Paul ran for president as a member of the Libertarian Party). If his fundraising continues at this pace, he might be tempted to do it. Something tells me it’s a possibility the Clinton camp isn’t exactly dreading.